1. Field of the Invention
The present invention relates generally to crop harvesting and more particularly to a portable thrasher for grain sampling.
2. Description of the Related Art
Various thrashers have heretofore been devised for harvesting grain crops. Thrashers designed for normal harvesting operations can be relatively large, complicated and expensive. These characteristics are consistent with the objectives of normal field harvesting operations, i.e. to maximize the crop yield in the shortest possible time with the lowest possible labor and fuel requirements.
Proper harvest timing can be important to maximize crop yields and also to obtain the best possible prices for the harvested crops. One timing factor involves the ripeness of the crops. Another factor involves their moisture contents, which can vary considerably over relatively short periods of time as the crops are exposed to precipitation and the drying effects of sun and wind. Harvesting a crop in a wet condition can result in a lower price being paid for it since crop buyers, such as cooperatives and grain elevators, often discount grain prices for excessive moisture content because higher moisture levels can cause problems of spoilage and heat buildup in the stored grain.
Relatively "wet" grain may require drying and/or mixing with drier grain for marketability. Grain buyers often compensate for these problems and extra processing costs by "docking" grain sellers for damp grain.
Crop moisture conditions in the fields can change in a few hours; for example, a heavy dew may cover a field early in the morning, and then substantially evaporate a few hours later. Thus, properly timing a grain harvest often involves timing within a matter of hours. Without hygrometers and other sophisticated equipment for determining moisture content, farmers and harvest workers often make estimates based upon their personal observations. However, such measuring and sampling methods can be relatively imprecise.
As an alternative, the harvesting equipment can be advanced into the field for a crop sample, which can then be analyzed for moisture content. However, much of the equipment designed for large scale field harvesting work is not particularly well suited for cutting and separating small samples, particularly moisture content analysis samples which generally require only a handful (e.g. about 250 grams or less) of grain. Some full-size equipment, therefore, tends to be wasteful when used for sampling since it thrashes considerably more grain than is needed for analysis purposes. Furthermore, transportation problems can be encountered with relatively large harvesting equipment, particularly when samples are needed from fields which are distant from each other. When remote fields are to be harvested, transporting large thrashers and combines to various distant locations can be expensive and inefficient when only small grain samples are needed.
A solution to some of these problems is to provide a portable thrasher, which can easily be transported from place to place and which is adapted for retrieving relatively small grain samples for moisture content analysis purposes. Such a thrasher is shown in the Brehon U.S. Pat. No. 4,417,593, and utilizes a beater and a fan system for thrashing grain both mechanically and pneumatically. However, the air handling system of the Brehon thrasher contributes substantially to its bulk, and it would be desirable to provide a more compact unit which can easily be carried by an individual. Furthermore, the Brehon thrasher is configured for feeding the grain heads downwardly into a conduit opening at the top of the thrasher, which might add the additional operational step of cutting the grain stalks prior to thrashing.
The present invention addresses some of these problems by providing a relatively compact thrasher which is adapted for gathering grain heads as they are found in the field.